MT
Margarita Torres-Aquino
  • Campus San Luis Potosi, Colegio de Posgraduados, Mexico
Research fields
  • Microbiology
In vivo and in vitro 31P-NMR Study of the Phosphate Transport and Polyphosphate Metabolism in Hebeloma cylindrosporum in Response to Plant Roots Signals
We used in vivo and in vitro phosphorus-31 nuclear magnetic resonance (31P-NMR) spectroscopy to follow the change in transport, compartmentation and metabolism of phosphate in the ectomycorrhizal fungus Hebeloma cylindrosporum in response to root signals originating from host (Pinus pinaster) or non-host (Zea mays) plants. A device was developed for the in vivo studies allowing the circulation of a continuously oxygenated mineral solution in an NMR tube containing the mycelia. The in vitro studies were performed on fungal material after several consecutive treatment steps (freezing in liquid nitrogen; crushing with perchloric acid; elimination of perchloric acid; freeze-drying; dissolution in an appropriate liquid medium).
Establishing a Symbiotic Interface between Cultured Ectomycorrhizal Fungi and Plants to Follow Fungal Phosphate Metabolism
In ectomycorrhizal plants, the fungal cells colonize the roots of their host plant to create new organs called ectomycorrhizae. In these new organs, the fungal cells colonize the walls of the cortical cells, bathing in the same apoplasm as the plant cells in a space named the ‘Hartig net’, where exchanges between the two partners take place. Finally, the efficiency of ectomycorrhizal fungi to improve the phosphorus nutrition of their host plants will depend on the regulation of phosphate transfer from the fungal cells to plant cells in the Hartig net through as yet unknown mechanisms. In order to investigate these mechanisms, we developed an in vitro experimental device mimicking the common apoplasm of the ectomycorrhizae (the Hartig net) to study the phosphorus metabolism in the ectomycorrhizal fungus Hebeloma cylindrosporum when the fungal cells are associated or not with the plant cells of the host plant Pinus pinaster. This device can be used to monitor 32Phosphate efflux from the fungus previously incubated with 32P-orthophosphate.
A Method for Radioactive Labelling of Hebeloma cylindrosporum to Study Plant-fungus Interactions
In order to quantify P accumulation and P efflux in the ectomycorrhizal basidiomycete fungus Hebeloma cylindrosporum, we supplied 32P to mycelia previously grown in vitro in liquid medium. The culture had four main steps that are 1) growing the mycelium on complete medium with P, 2) transfer the mycelia into new culture solution with or without P, 3) adding a solution containing 32P and 4) rinsing the mycelia before incubation with or without plant. The main point is to rinse very carefully the mycelia after 32P supply in order to avoid overestimation of 32P efflux into the medium.
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